1. Field of the Invention
The present invention relates to a bearing assembly, and more particularly to a bearing assembly for a heat dissipation fan. The bearing assemble enables the lubricant to flow freely inside the heat dissipation fan without clogging by contaminant.
2. Description of Related Art
With reference to FIGS. 5 and 6, a conventional heat dissipation fan assembly (5) is composed of a housing (50), a stator (60), a bearing (70) and a rotor (80).
The housing (50) has a cylindrical seat (52) formed on a bottom plate (51) and provided with a lubrication chamber (521) having therein a friction pad (64) and a positioning groove (53) defined around the seat (52).
The stator (60) includes a sleeve (61) and a circuit board (62) securely connected to the sleeve (61). The bearing (70) has a centrally defined through hole (71) and the rotor (80) has a shaft (81) extending out to correspond to the through hole (71) of the bearing (70) and formed with a neck (82) at a free end of the shaft (81).
When the heat dissipation fan is assembled, the shaft (81) extends through the through hole (71), the sleeve (61) and a retaining plate (63) to allow the retaining plate (63) to be securely received in the neck (82) of the shaft (81). Then, the sleeve (81) is received in the groove (53) with the free end of the shaft (81) abutting the friction pad (64) and the retaining plate (63) received in the sleeve (61). After the assembly of the heat dissipation fan, it is noted that only the bottom of the lubrication chamber (521) of the housing (50) is closed, the top of the lubrication chamber (521) is open to the air, such that contaminant may fall into the lubrication chamber (521) and attach the periphery of the bearing (70). Eventually, the contaminant will clog the flow of lubrication oil inside the lubrication chamber (521) and thus causes the life span of the heat dissipation fan short. Furthermore, when the heat dissipation fan is in use, it can not be operated up-side-down for the lubrication oil in the lubrication chamber (521) may easily flow out of the lubrication chamber (521) to shorten the life of the fan.
Again, when the rotor (80) is in operation, the lubrication oil in the lubrication chamber (521) will flow upward along the shaft (81). However, when the shaft (81) is assembled inside the lubrication chamber (521), the downward movement of the shaft (81) together with the retaining plate (63) increases the pressure inside the lubrication chamber (521), which hinders the downward flow of the lubrication oil along the shaft (81) back to the lubrication chamber (521) and thus the lubrication oil on the shaft (81) will be gradually dried out and shortens the life of the entire assembly.
To overcome the shortcomings, the present invention tends to provide an improved bearing assembly to mitigate and obviate the aforementioned problems.
The primary objective of the present invention is to provide a bearing assembly having a cap securely mounted on top of the bearing to stop the lubrication oil from flowing outward to contaminate the heat dissipation fan.
Another objective of the invention is to provide the cap to be engaged with the bearing in an water tight manner such that the bearing assembly is able to operate in any angle without the worry of loss of lubrication oil.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.